How do I scale my reference images correctly within Blender and is there an easier way?
You are using background images.
The way you scale a background image is by adjusting the Size value. It is located at the bottom of the background image settings in the properties region (N) in the 3D view.




However you may find it easier to use Image empties instead of the background images.
Question links:
How to set-up the perspective view based on a reference image?
Drag background images in 3D view?  

cgCookie tutorial and an older cgCookie tutorial